


Fit love into the equation

by Ravendor_Neera



Category: Harry Potter - J. K. Rowling
Genre: Bookshop Owner Remus Lupin, Chance Meetings, Flirting, M/M, Teacher Sirius Black, cuteness, light mood
Language: English
Status: Completed
Published: 2020-04-24
Updated: 2020-04-24
Packaged: 2021-03-01 20:12:56
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,349
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23822869
Author URL: https://archiveofourown.org/users/Ravendor_Neera/pseuds/Ravendor_Neera
Summary: My contribution to girlwithacrown’s "Finish This Fic" challenge.The first part is "Dust on the counter-Finish this fic" and you can find it on her profile!This is my second half, the first summary being briefly - "Remus is sitting in his bookshop during coronavirus lockdown, the weather is dreadful and Sirius comes looking for a book".Enjoy!
Relationships: Sirius Black/Remus Lupin
Kudos: 32





	Fit love into the equation

**Author's Note:**

  * For [girlwithacrown](https://archiveofourown.org/users/girlwithacrown/gifts).



> I'm also on [Tumblr](https://www.tumblr.com/blog/here-is-thegreatmoon)  
> Come say hi!

Remus stared at him. -“I happen to have many books- he fought back a laugh because it would have probably seemed rude, but he was amused- can you…”  
\- “A book about physics... I really hope you have it because I really need it. It’s called...”   
In the light of the entrance, now that Remus took his time to look, he had the feeling he had seen this man before. There was something familiar in those grey eyes...  
\- “Black?”  
Something had clicked in Remus’ mind at the mention of physics. Black. _Sirius Black_. The class ‘he’s smart but he needs to apply himself’ guy, except that he was really good in physics, in which he effortlessly always got the highest grades hardly ever opening the book. Black. Who sat in the back, doodling through most of lessons, leaning back on the chair’s hind legs. Sirius Black. His hardest school crush. He hadn’t seen him since graduation. It was now almost painful to see he got even better with age.  
The other man looked up in surprise at hearing his name and regarded Remus more attentively, his bright eyes trailing over his face and figure.  
-“Have we... wait- his eyes went wide for a moment and he held up a hand, eyes fixed on him- high school. Third section... Lupin.”  
-“Right”  
Something in Remus hummed with satisfaction at the notion of being remembered. Probably it was that part of him that during his teens had always felt too shy and insignificant to leave a mark. They were never really friends. Just class mates who got on well. Once they had been paired up for a literature research, much to Remus’ secret joy and desperation. Each pair had been given a topic and an author and then they had to present it to the rest of the class. Remus had to explain him a whole poem by Wordsworth word by word because he just didn’t seem to get the poetic meaning behind the words. Metaphors and poetry were obscure to him as much as equations and physics were to Remus. After that, they sometimes helped in each other with their respective strong subjects.  
-“Please, come in- Remus gestured, moving to close the door- I can’t say how... odd this is! I haven’t seen you since graduation. Wait a second.”  
He rushed behind the counter and took a clean towel from the closet in the back. Then handed it to Black.  
-“Heard you moved to another town…” he continued.  
Black ran the towel and a hand through his dark, wet hair and Remus was flung back to a time when he daydreamed about running his fingers through those strands of hair, while pretending to listen to math lessons, two rows to the right from his desk.  
-“Yeah, I moved for university and then moved for good. I got back to arrange some family matters and I got stuck here because of the quarantine. Can’t go back as of now. Which brings me to the matter in hand: I left all my books at my place and I really need _Deep Down Things_ by B. Schumm… Please tell me you have it.” Remus went to check on the inventory in his computer.  
-“Yes, I should have some copies in the science shelf… You can find it on e-book anyway. Is it worth breaking the quarantine and braving this weather?”  
Black shook his head:  
-“I hate books on screen, I can’t read them the same way. And I just can’t teach a bunch of teenagers without it. It’s super clear and accessible.”  
-“You are a teacher?” Remus was genuinely surprised.  
-“Yup. Physics, high school- replied Sirius, with a mischievous smile- Would you believe it?”  
Remus smiled back:- “I’d never have seen it coming. But you were actually very smart, so why not?” then he moved to get the book.  
Black followed, looking around:  
-“You work here?”  
-“Yes, I own it, actually”  
-“Of course you ended up opening a bookstore… It befits you, from what I remember. Lit nerd… just joking” Black added, quickly.  
-“No worries. I was… still am, actually. Here it is!”  
Remus picked up the book from the shelf. The subtitle read: _The breath-taking beauty of particle physics_.  
-“Particles…- mused Remus looking at the cover- I think I should remember more from school but I’m afraid I can’t… Although I think I read something cool some time ago… about particles and entanglement and this Dirac equation that says that once these particles come in contact, they can’t be seen as a separate systems but only as one, as they are influenced by each other no matter how far apart they may be… they called it the equation of love…” he looked up abruptly, eyes wide with embarrassment. It sounded very cheesy. He just wanted to disappear in the ground. But Black was smiling, amusement in his grey eyes:  
-“I’m sorry but Dirac’s equation has nothing to do with love, nor really has entanglement. I had to break it to loads of students, so don’t feel embarrassed. It’s a common mistake. I think the internet is to blame- he leaned on the side of the shelf with his arms crossed and explained, his gaze trailing over Remus- To make it simple, Dirac’s equation is sort of a relativistic version of Schrödinger’s, you know, the guy of the cat in the box, and it refers to particles that move in an infinite ocean of particles and for each there’s another that has same mass and opposite charge. And entanglement is an extremely unclear topic even for scholars, there’s still so much we don’t know… but anyway it is a phenomenon that only makes sense for microscopic systems while lovers are a macroscopic system… Although I’ll grant you one could say there’s something romantic in it… metaphorically speaking.”  
Remus would never have believed that physics could be so interesting, all of a sudden. If their teacher had been even remotely as sexy as Sirius was in that moment, he may have had higher grades. He looked away, probably flushed, and handed him the book. He was ready to bet Black was the favourite teacher of many many students...  
-“Thanks for the explanation, really… I feel kinda silly”  
-“Don’t- said the other man, stretching a hand to take the book from his. As he did so, he placed his fingers on Remus’- As I said, it’s a common mistake” he smiled and walked back to the counter.  
Remus shook himself out of a trance and followed. What was that sort of energetic field he had felt when their fingers brushed? He recollected himself and played it cool.  
-“I’m positively surprised by your mention of metaphors. You’ve finally grasped figures of speech, I see…?” he commented as he scanned the book and took Sirius credit card.  
-“Not exactly, but I’ve started reading poetry in free time, I felt I needed to fill the gap…I feel I still have a long way to go but I’ve improved. For example, I’ve just come to understand what Wordsworth meant with _My heart leaps up_ …” he replied, eyeing Remus.  
-“Maybe you can ask your Lit colleagues to help out…” Remus offered, handing him book and receipt.  
But Black shook his head, damp hair falling on his eyes: - “ I’ve just had a better idea.”  
He took the receipt, flipped it to the blank side, snatched a pen from the counter and scribbled a number on the back, then slid it to Remus.  
-“Call me and I’ll tell you more about entanglement and atoms and you can explain me figures of speech. Then, when this quarantine is over, we’ll see if we can fit love into the equation. How does it sound?”  
Remus stared, taken aback. Was that really happening to him?  
-”Sounds like a very good periphrasis” he replied, unable to withhold a grin.  
Sirius winked and shot Remus an illegally smug, flirty smile then left, waving before closing the door. Remus stared at the receipt and thought that, all in all, he felt not that guilty about the online shop anymore.


End file.
